This invention relates in general to time-space-time (T-S-T) telecommunication switching systems, and in particular to a T-S-T switching system having a modularly expandable space stage.
Time-space-time (T-S-T) switching systems are a configuration of digital switching elements providing both time and space translation between channels of time division multiplexed (TDM) telecommunications transmission lines. The T-S-T network of a switching system interconnects digital bi-directional TDM communication lines with TDM communication involving the sharing of single transmission paths, individually, in time, to provide multiple channels in a single transmission medium. The construction of such a T-S-T network comprises the connection of a spacial stage between the two time stages.
Increasing the network capacity of a T-S-T digital switching system entails increasing the size of the time and space switching stages. The consequence of this network growth is that doubling the number of time stages increases the size of the space stage by a factor of two squared or 4 times.
Provisions for such network growth must be anticipated when such a T-S-T network is configured. Thus, a central exchange anticipating a certain amount of growth must ultimately install a space stage four times greater than its present requirements.
It would therefore be advantageous to provide a space stage for the T-S-T network of a digital switching system which has the capability to grow modularly with the time stage.